|
2SEETV QUICK GUIDE TO CHOOSING A NIGHT VISION
CAMERA
The main
criteria for selection of a night vision CCTV camera are:
Resolution – This
is described by the number of vertical lines the camera can display. If the
camera is looking at a test card of black vertical lines on a white background
it will be able to distinguish a change from black to white 380 times for a
380TVL (Television Lines) camera.
Most
domestic television sets cannot display more than 400TVL at best so you will
need to use a high resolution CCTV monitor to benefit from the higher resolution
cameras.
However, if using a
digital video recorder, the images will still be recorded in high resolution and
should an incident occur the images can be reviewed on a better quality monitor.
Sensitivity –
Measured in units of Lux, it describes when the camera will change from day to
night vision.
Lens
focal length – A
3.6mm lens will give a 72 deg angle of view so is wide angle. A 6mm lens gives
52 deg which will make objects larger but you loose side coverage.
Cameras
with a varifocal lens allow you to adjust the focal length at the time of
installation. Hence you can frame the picture to give the optimum field of view.
Note, we
can supply KT&C cameras with alternative focal lengths upon request.
CCD
– Sony, the original manufacturers of the CCD are still the market leaders. The
Sony Super HAD CCD gives excellent results. Most of our cameras are based on the
Sony CCD as tests have shown these products to give the best results. The EXView
version has increased sensitivity in both day and night modes. The sensitivity
to infra red light is improved by 4 times.
Infra
Red beam transmission distance
– The IR beam can be thought of as an invisible torch beam. It’s invisible to
the human eye but not the camera. Like a torch beam it will fade with distance.
At night the further objects are from the camera the dimmer they will become.
The figures quoted are the manufacturers’ specification. It is advised to work
well within these figures and not expect bright images at the maximum distance.
Night
vision cameras work by objects reflecting back the infra red beam to the camera.
If the camera is looking at black tarmac it will display very little but as soon
as a person walks towards the camera they will start to reflect the beam and the
camera will display images.
Similarly, grass can have
an adverse effect on night-vision cameras. A property of grass is that it
absorbs infra red beams. This has the effect of making the camera work harder as
the image will appear dimmer. A person walking across grass will reflect back
the IR beam but may appear as a whiter figure.
It is only monochrome
(black and white) cameras that are responsive to IR light. A camera described as
a colour night vision camera is colour during daylight and automatically
switching to monochrome in low light conditions.
True
Day/Night Cameras - All cameras have an
IR filter to limit the effect of IR rays from the sun. If the filter was present
all the time it would have a detrimental effect on night-time viewing. True
Day/Night Cameras have an Infra Red Cut Filter. This physically moves in front
of the lens during day light and is removed when the light level falls.
True Day/Night Cameras give superior images under varying conditions.
Other cameras use an
electronic method to compensate for the changing conditions.
True Day/Night Cameras are
the Concept Pro VL30 and VL40 range. The DSIRHRV dome camera is also True
Day.Night.
OUR BEST SELLING NIGHT VISION CAMERAS
Concept Pro VLP15 Range
Superb
quality cameras backed by a 5 year warranty. A choice of resolutions from 380TVL
to 550TVL. The IR range of up to 15 Metres makes this product suitable for most
home or small business applications. The Sony SuperHAD CCD gives improved
sensitivity, particularly at night.
Concept Pro VLP30 Range
This
range has a varifocal lens with a focal length adjustable from 4 to 9mm. This
makes it suitable for longer ranges or where greater magnification of objects is
required. They have an IR distance of up to 30 metres. A Sony SuperHAD
gives improved sensitivity, particularly at night. True Day/Night.
Choose
the VLP3026 camera for night-time observation of long driveways or car parks
adjacent to larger premises.
All products in Concept Pro range are backed by the Concept Pro 5
year warranty.
Concept Pro VLP40 Range
Built into a slightly larger casing,
complete with a heater and a blower to optimise the operating temperature, these
products offer performance suitable for larger buildings. As True Day/Night
cameras they give excellent results in varying conditions.
The VLP4026 has a high resolution of
550TVL and a large array of LEDs to give 40 metre night-time viewing range. The
bracket can be swivelled to allow for mounting on a horizontal surface, such
under the eaves of building. As such the angle of adjustment is 30 degrees in
either direction. If the camera need to look along a wall it is better to select
the VLP4526 which has a fully rotatable bracket.
The VLP4526 has an even great IR range
of 50 metres. Unlike some long range cameras that achieve the IR distance by
focusing the beam into a "spot" pattern the VLP4526 maintains a good beam
spread. This makes it one of the finest security cameras for long range
operation. Choose
this camera for night-time observation of long driveways or car parks adjacent
to larger premises.
Dome Cameras
In these type of security cameras the
module is fitted into a dome or eye-ball housing.
CG-50
KT&C Super Night Vision Monochrome External CCTV Camera - Zero Lux
KT&C,
based in Korea, have been producing cameras of renowned quality for many years.
This model uses the Sony CCD and has a strong and weather resistant case and
mounting bracket. Choose this model if the main application is night-time
monitoring and the budget will not allow for colour day time viewing.
The CG-50
is fitted with a 3.6mm lens which is ideal for most applications.
|
